The present invention provides novel emulsions which comprise oil bodies. The invention also provides a method for preparing the emulsions and the use of the emulsions in various products that are topically applied to the surface area of the human body.
Emulsions are mixtures prepared from two mutually insoluble components. It is possible to generate mixtures of homogenous macroscopic appearance from these components through proper selection and manipulation of mixing conditions. The most common type of emulsions are those in which an aqueous component and a lipophilic component are employed and which in the art are frequently referred to as oil-in-water and water-in-oil emulsions. In oil-in-water emulsions the lipophilic phase is dispersed in the aqueous phase, while in water-in-oil emulsions the aqueous phase is dispersed in the lipophilic phase. Commonly known emulsion based formulations that are applied to the skin include cosmetic products such as creams, lotions, washes, cleansers, milks and the like as well as dermatological products comprising ingredients to treat skin conditions, diseases or abnormalities.
Generally emulsions are prepared in the presence of a multiplicity of other substances in order to achieve a desirable balance of emulsification, viscosity, stability and appearance. For example, the formulation of emulsions usually requires at least one, and frequently a combination of several, emulsifying agents. These agents facilitate the dispersal of one immiscible phase into the other and assist in stabilizing the emulsion. A comprehensive overview of emulsifying agents and their applications may be found in Becher, P. Encyclopedia of Emulsion Technology, Dekker Ed., 1983. Active agents beneficial to the skin, such as compounds to treat skin diseases, are also frequently formulated as emulsions in order to enhance their stability and to facilitate application of the active agent to the skin.
In the seeds of oilseed crops, which include economically important crops, such as soybean, rapeseed, sunflower and palm, the water insoluble oil fraction is stored in discrete subcellular structures variously known in the art as oil bodies, oleosomes, lipid bodies or spherosomes (Huang 1992, Ann. Rev. Plant Mol. Biol. 43: 177-200). Besides a mixture of oils (triacylglycerides), which chemically are defined as glycerol esters of fatty acids, oil bodies comprise phospholipids and a number of associated proteins, collectively termed oil body proteins. From a structural point of view, oil bodies are considered to be a triacylglyceride matrix encapsulated by a monolayer of phospholipids in which oil body proteins are embedded (Huang, 1992, Ann. Rev. Plant Mol. Biol. 43: 177-200). The seed oil present in the oil body fraction of plant species is a mixture of various triacylglycerides, of which the exact composition depends on the plant species from which the oil is derived. It has become possible through a combination of classical breeding and genetic engineering techniques, to manipulate the oil profile of seeds and expand on the naturally available repertoire of plant oil compositions. For an overview of the ongoing efforts in his area, see Designer Oil Crops/Breeding, Processing and Biotechnology, D. J. Murphy Ed., 1994, VCH Verlagsgesellschaft, Weinheim, Germany.
Plant seed oils are used in a variety of industrial applications, including the personal care industry. In order to obtain the plant oils used in these applications, seeds are crushed or pressed and subsequently refined using processes such as organic extraction, degumming, neutralization, bleaching and filtering. Aqueous extraction of plant oil seeds has also been documented (for example, Embong and Jelen, 1977, Can. Inst. Food Sci. Technol. J. 10: 239-243). Since the objective of the processes taught by the prior art is to obtain pure oil, oil bodies in the course of these production processes lose their structural integrity. Thus, the prior art emulsions formulated from plant oils generally do not comprise intact oil bodies.
Although fossil oil based products dominate certain markets, in other applications, oils derived from plant sources and fossil sources are in direct competition. Lauric oils, for example, which are widely used in the manufacture of detergents, are obtained from fossil oils as well as from coconut oil and more recently from genetically engineered rapeseed (Knauf, V. C., 1994, Fat. Sci. Techn. 96: 408). However, there is currently an increasing demand for biodegradable sources of raw materials. The plant oil body based emulsions of the present invention offer an advantage over similar mineral oil based formulations, in that the oil fraction is derived from a renewable and environmentally friendly source.
U.S. Pat. No. 5,683,740 to Voultoury et al. and U.S. Pat. No. 5,613,583 to Voultoury et al. disclose emulsions comprising lipid vesicles that have been prepared from crushed oleagenous plant seeds. In the course of the crushing process, oil bodies substantially lose their structural integrity. Accordingly, these patents disclose that in the crushing process, 70% to 90% of the seed oil is released in the form of free oil. Thus the emulsions which are the subject matter of these patents are prepared from crushed seeds from which a substantial amount of free oil has been released while the structural integrity of the oil bodies is substantially lost. In addition, the emulsions disclosed in both of these patents are prepared from relatively crude seed extracts and comprise numerous endogenous seed components including glycosylated and non-glycosylated non-oil body seed proteins. It is a disadvantage of the emulsions to which these patents relate that they comprise contaminating seed components imparting a variety of undesirable properties, which may include allergenicity and undesirable odour, flavour, colour and organoleptic characteristics, to the emulsions. Due to the presence of seed contaminants, the emulsions disclosed in these patents have limited applications.
The present invention relates to novel emulsion formulations which are prepared from oil bodies. The emulsion formulations of the subject invention are obtainable in non-toxic and food grade forms. In addition, the emulsion formulations are advantageously prepared from an oil body preparation which is creamy in texture and thus may be readily applied in a variety of products that are topically applied to the skin. The present inventors have found that the oil body fraction of living cells is useful in the formulation of personal care and dermatological products. Broadly stated, the present invention provides an emulsion formulation for topical application or for application to the surface area of the human body comprising washed oil bodies derived from a cell.
The invention also provides methods for preparing the emulsion formulations and the use of the emulsion formulations for the application to the surface area of the human body.
Accordingly, the present invention provides a method for preparing emulsion formulations for topical application comprising: 1) obtaining oil bodies from a cell; 2) washing the oil bodies; and 3) formulating the washed oil bodies into an emulsion for topical application to the surface area of the human body.
In a preferred embodiment of the invention, the washed oil body preparation is obtained from plant seeds, including seeds obtainable from flax, safflower, rapeseed, soybean, maize and sunflower. Accordingly, the invention provides a method for preparing an emulsion formulation for topical application from plant seeds comprising:
(a) grinding plant seeds to obtain ground seeds comprising substantially intact oil bodies;
(b) removing solids from the ground seeds;
(c) separating the oil body phase from the aqueous phase;
(d) washing the oil body phase to yield a washed oil body preparation; and
(e) formulating the washed oil body preparation into an emulsion for topical application.
In a preferred embodiment of the invention, a liquid phase is added to the seeds prior to or while grinding the seeds.
In a further preferred embodiment of the invention, formulating the emulsion comprises stabilizing the washed oil body preparation to prevent degradation of the oil bodies either by physical forces or chemical forces.
The emulsions of the present invention can be used in a wide range of applications including in the preparation of personal care and dermatological products. Additional advantages and features of the present invention will become apparent after consideration of the accompanying drawings and the following detailed description of the invention.